Methods: We compiled biweekly COVID-19 case counts of 274 zip code tabulation areas (ZCTAs) in Arizona from October 21, 2020, to November 25, 2021, a time spanning multiple waves of COVID-19 case growth. Within each biweekly period and using multiple regression analysis, we tested the associations between the growth rate of COVID-19 cases and the population composition in a ZCTA including race/ethnicity, income, employment and age. We then compared the associations across time periods to discover temporal patterns of health disparities.
Results: The association between the percentage of Latinx population in a ZCTA and the COVID-19 growth rate was positive before March 2021 but gradually converted to negative afterwards. The percentage of Black population in a ZCTA was not associated with the COVID-19 growth rate at the beginning of the study but became positive after January 2021. Similarly, the positive association with the unemployment rate emerged after July 2021. Meanwhile some health disparity patterns persisted throughout the study period, including the negative associations of the COVID-19 growth rates with the poverty rate and the median age of residents in a ZCTA. Based on these findings, we identified 37 ZCTAs that are highly vulnerable to future fast escalation of COVID-19 cases.
Discussion and Conclusions: As the pandemic progresses, vulnerabilities associated with Latinx ethnicity improved gradually, possibly bolstered by culturally responsive programs in Arizona to supporting Latinx communities. Still communities with disadvantaged social determinants of health continued to struggle. Our findings inform the need to adjust current resource allocations to support the design and implementation of new interventions addressing the emerging vulnerabilities at the community level.